This invention relates to an improved light-weight battery jar formed of a plastic material and having substantial strength in the transverse direction.
In the past battery jars for storage batteries have been typically formed of a heavy material such as metal and/or hardened rubber. The steel or metal structure has been required because of the weight of the battery plates which are typically comprised of lead or a lead compound. These plates are particularly heavy when used in storage batteries of the type utilized by industry wherein the plates are typically in the neighborhood of 41/2 feet long. Thus, when a plurality of such plates are placed in a battery jar together with an electrolyte, a substantial pressure bears against the side walls and bottom of the battery jar. In addition, the acid in the electrolyte tends to eat away at the metal. Accordingly, a liner consisting of hard rubber has been typically utilized to isolate the steel shell of the battery jar from the electrolyte contained therein. The combination of providing a strong metal casing with a hard rubber lining has resulted in a heavy, cumbersome and expensive battery jar arrangement.
An example of prior art battery jars is disclosed in Marx U.S. Pat. No. 897,472 wherein an acid barrier of hard rubber is provided in the inside of a battery jar casing which includes a sheet of metallic material having two horizontal ribs extending about the periphery thereof to add strength to the casing. This battery provides no means for preventing the battery casing from bulging in the transverse direction except for the pair of ribs which are positioned at the top and bottom of the battery jar. Thus, over a substantial length of the battery no means are provided for strengthening the battery againt transverse bulging forces.
In order to overcome the problem of combining a hard rubber acid barrier with a steel outer casing Boyer developed, as disclosed in U.S. Pat. No. 1,425,574, a battery jar which is made solely from hard rubber. The hard rubber casing has several ribs positioned horizontally about the periphery thereof in order to provide support against lateral bulging. This battery jar required both an inner and outer hard rubber casing in order to provide the necessary support for the lead acid storage cells contained therein. Accordingly, the battery was both heavy and bulky due to the substantial thickness of the hard rubber required for supporting the battery.
Other known battery casings have a plastic outer shell which provides both an acid barrier and support for the battery. However, these battery casings are typically used for storage batteries of the type utilized in automobiles which batteries do not have the heavy elongated plates typically utilized in industrial applications.
Accordingly, it is an object of this invention to provide a battery jar for supporting elongated battery plates such as utilized in industrial applications.
It is another object of this invention to provide an economical and relatively lightweight battery jar made of plastic material for supporting heavy duty battery plates therein.